1. Field of the Invention
The present invention relates to a rotary engine and, more particularly, an improvement thereof which avoids the generation of chatter marks in the trochoidal inner peripheral surface of the rotor housing due to a resonance of the apex seals mounted at apex portions of the rotor and the rotor housing.
2. Description of the Prior Art
In the Wankel type rotary engine which generally comprises a casing composed of a rotor housing having a trochoidal inner peripheral surface and side housings which close the opposite ends of said rotor housing, an eccentric shaft and a polygonal rotor adapted to eccentrically rotate around said eccentric shaft with apex portions thereof sliding over said trochoidal inner peripheral surface, chatter marks are generated in said trochoidal inner peripheral surface, due to a resonance of the apex seals provided at said apex portions of the rotor and the rotor housing. In a rotary engine of the aforementioned type, the rotor housing generally includes an inner wall portion, which provides said trochoidal inner peripheral surface, and an outer wall portion, which encloses said inner wall portion therein so that a cooling water passage is defined therebetween, and through which cooling water is circulated during the operation of the engine. The inner and outer wall portions are generally formed as an integral member together with a plurality of stay portions which bridge and connect the two wall portions, while said cooling water passage is defined to be separate individual passages defined by the inner and outer wall portions and two adjacent stay portions. The inner wall portion is generally formed as a relatively thin wall structure, supported by the outer wall portion by means of the stay portions arranged and spaced therealong and, because of this, when the individual apex portions or apex seals of the rotor successively traverse over individual portions of the inner wall portion, thereby exerting a kind of oscillating force thereto, the inner wall portion supported by the spaced stay portions is caused to oscillate. If the oscillation of a particular portion of the inner wall portion resonates with the oscillating force applied thereto, the inner surface of the particular portion is subject to a strong rubbing action applied by the apex seals, thereby causing a heavy local wearing action generating a chatter mark defined by a series of worn portions.